Etching, which entails removing material from a surface, is commonly used in the fabrication of semiconductor devices and may constitute roughly one-third of semiconductor device manufacturing. Critical challenges in device fabrication are reliably etching ever-smaller features and preserving surface fidelity.
Etch methods used in research and industry include wet chemical etching, which employs liquid chemicals or etchants for material removal, and dry etching, which utilizes gaseous chemicals or high energy ions for material removal. Wet chemical etching is generally isotropic. If directionality is important for high-resolution pattern transfer, wet etching is normally not used. Dry etching can be carried out with high energy particle beams, a gaseous chemical reaction, or a combination of both to achieve anisotropic etching. Reactive ion etching (RIE), which uses both physical and chemical reactions to etch high resolution features, is among the most widely used dry processes in industry and research. However, the high energy of ions in RIE can be a key culprit in causing surface disorder or damage and material mixing. Damage of even one nanometer in depth can be detrimental to the performance of a semiconductor device in next-generation technology nodes.